Anti-skid surface covering



Patented Apr. 28, 1955 2,706,936 ANTI-SKID SURFACE COVERING Gilbert G.Willson, In, St. Paul, Minn., assignor to Minnesota Mining &Manufacturing Company, St. Paul, Minn a corporation of Delaware NoDrawing. Application June 21, 1948,

Serial No. 34,3 Claims. (Cl. 94-5) This invention relates to anti-skidfloor coverings of the nature of flexible and water-resistant sheetmaterial having a roughened resinous anti-skid surface.

While the product of this invention is of general utility in providinganti-skid surfaces on floors, Stairways, aircraft wing-walks, and thelike, it has been found to be t Sliding of ammunition, striking nailedshoes, etc., must cause no sparking, particularly in the vicinity ofgasoline or powder storage. The anti-skid surface should not abrade orcut the feet of personnel who must on occasion walk barefoot over it incarrying out their assigned duties. It should be easily cleaned, withoutexcessive wear on mops or brushes.

Softer particulate surfacings in place of the more common mineralabrasive grid particles have found some application in providinganti-skid surfacings. Cork particles, for example, ofler a degree ofprotection against slippage when properly bonded to the walkway surface.But under the service conditions'encountered on aircraft carriers,anti-skid surfaces containing cork particles are found to be lesseffective in preventing slipping than those containing mineral abrasivegrit. Cork and simi-' lar particulate material swells somewhat undercontinued exposure to water, and then away from the resinous binder withwhich it is bonded to the flooring. Furthermore, such anti-skid surfaceseven under dry conditions have a somewhat shorter useful life than hasthe mineral type anti-skid surface.

In a popular type of anti-skid surface covering, hard bonded to awaterproofed fabric base with a binder material consisting largely of athermally hardened phenolic resin. The sheet material is then attachedto the sheet steel, concrete, or other floor or deck surface by means ofa suitable tough and adherent adhesive cement. The anti-skidwear-resisting surface is provided by the particles of mineral, theresinof the floor surface with surfaces as the or broken away.

I have now found that irregularly shaped, angular grid particles ofprocured synthetic resins or analogous bodies having properties ofhardness, resilience, toughness and the like as hereinafter defined, andin particular the moulded phenolic resins, may replace the abrasivemineral particles of these prior art anti-skid walkway surfacings, withsurprising results in terms not only of anti-skid efiiciency but also interms of prolonged wearresistance.

I have found that particularly desirable and unexpected results areobtained wh crushed fully cured phenol-aldehyde resin moulding resinapplied as a en I employ particulate 0 compositions as the grid materialin my-novel resinous anti-skid floor surfacing sheet material. Suitablematerial is available in large volume from the manufacturers of mouldedphenol-aldehyde radio cabinets, telephone hand-sets, and similarobjects, in the form of rejected or broken pieces, sprues, fiashings, orthe like. These compositions ordinarily contain a high proportion, e.g., 50-80%, of wood flour or other inert filler. They are mouided orcured at relatively high temperatures and pressures, to a fully cured,hard and dense state. As such, they are highly water-resistant.

Cast phenolic resins, which are poured into moulds and then allowed toharden for relatively long times at relatively low or moderatetemperatures, have substantially equivalent properties. These and otheranalogous phenolic resinous products are included within the scope ofthe term thermally cured phenolic resin mouldings as employed herein.

These relatively massive moulded products may be readily reduced todesired dimensions by free crushing on rolls, followed by screening todesired size. In carrying out these operations, it has been found thatmaterials particles for my anti-skid ducible to the specific dimensionsrequired substantially In contrast, the abrasive minerals, whethernatural or synthetic, cannot be reduced to the relatively large-sizeparticles required for anti-skid surfacings without at the same timeproducing considerable quantities of much smaller particles or fines.

s far as properties of the finished anti-skid article are concerned, theabrasion and impact resistance of the particles is of importance. I haveobserved without formation of dusts bination of resiliency, toughness,inmpact resistance, and analogous properties of my novel grit materials,as evidenced by their peculiar reaction to crushing, is such thatindividual grams, while readily broken from the strength. Furthermore,the I substantially no reduction to fines are completely clean and freefrom surface-adherent dust, so that the resinous binder of the sheetproduct forms a firm adherent bond directly to the surface of the grain.

In making sheet material suitable for application as anti-skidsurfacing, I may proceed as follows: I first take a sheet of cottondrills cloth of any suitable width, and saturate the same, e.thermoplastic resin.

disclosed in the afore-mentioned patents. v

Both surfaces of the treated cloth are next coated with 0.15 lb. per sq.yd. of a soft, adherent phenolic 60% solution in a mixture of water andethylene glycol monoethyl ether, and the coated sheet is then hung upand heated for 1 /2 hours at synapse a P. The phenolic resin, whichthereby only partially cured. providing improved adhesion resin bond.

The resin bond is next applied to one surface of the cloth base, overthe last-described coating. This bond consists of 0.139 lb. per squareyard of a phenolic resin made from one mol of phenol and 1.4 mols offormaldehyde, with alkaline catalyst, and which is dissolved in amixture of water and ethylene glycol monoethyl ether. This resin rapidlysets up on heating to provide a hard, tough, and adherent bond.

As soon as the viscous resin bond coat is spead over the treated cloth,the resinous grit material is applied. This grit material consists ofcrushed and graded moulded phenolic resin; it has a specific gravity ofabout 1.4, and its surface can be scratched by calcite but not bygypsum. It is supplied as particles of from 56 to 80 grit size, theaverage being approximately 60. This is approximately equal to the sizeNo. l or No. 1 /2 flint sandpaper. The grit is pressed into the resinbond, and excess grit is shaken off, leaving approximately .54 lb. ofgrit per square yard. The coated sheet is heated to remove solvent andpartially cure the resin bond.

is a slow-curring type, is It acts as a priming coat, between treatedcloth and it is then given a surface sizing coat of 0.460.48 lb. per sq.yd. (dry basis) of the same binder material but at somewhat greaterdilution. The coated and sized sheet is finally cured for 12-14 hours at175 F., then for l-3 hours at 212 5., and finally for 4-6 hours at 248F.

The resulting sheet product is sufliciently flexible so that it may befitted and cemented to somewhat curved or irregular flight decksurfaces. it is of such excellent waterproofness that it does notsoften, nor lose quantities of the resin particles when subjected tofoot tra'fiic, after prolonged periods of immersion in sea-water. Whensecured in position on flight decks or the like, it provides aneffective and long-lasting anti-skid surface which does not causenoticeable wear of shoe soles or rubber tires and is completelynon-abrasive toward steel cables.

A specific construction has been described which provides properties ofparticular desirability in connection with flight decks of aircraftcarriers. This particular construction is not limited to suchapplications, but may be employed to advantage in many other locations.For example, the reduction in weight obtained by using my resinous gritin place of mineral type abrasive grit makes the new constructionvaluable for forming anti-skid walkways on aircraft.

resin particles is important where grit loosened or worn from anadjacent anti-skid walkway might be pressed into contact with polishedsurfaces or be drawn into bearings, since scratching of such polishedsurfaces is thereby avoided. The grit-coated surface produces no sparkswhen struck by steel articles. Workman can safely w'alk bar'efooted 'onsuch surfaces without discomfort.

Many variations in particularly 'in 'v'iew of the following discussion.any strong and flexible fabric or fibrous sheet may be protected withany suitably flexible, strong, adherent and water-resistantthermoplastic resinous impregnating agent to provide a flexible base forthe anti-skid surfacing. Depending on the type of surface to be givenanti-skid properties, it may also be possible to form and cure theanti-skid surface on a relatively rigid pie-formed shaped body, or evento form and cure it directly on the base surface, as in the case of woodfloors, for example. However, it is ordinarily more convenient, andmakes for a much more uniform and superior product, to provide aflexible p're-cured surfacing material such as hereinabove described,and subsequently to cement such product to the walkway surface.

The resinous binder composition nection with the above example istypical of phenolic binders employed in the coated abrasive art, andforms no part of the present invention. Any analogous binder compositionproviding equivalent adhesion, toughness, water resistance, and otherrequired properties may be used, and many such materials are known 'tothe art.

While heavily loaded phenolic or other resinous compositions are notordinarily suitable as binders and surface sizes due to their greatlyincreased viscosity, neve'u theless some loading of these materials ispossible of grit used in making The nonabrasive quality of the theconstruction of my novel resinous anti-skid sheet material will becomeapparent,

Thus,

described in coniii often is advantageous. Wood flour, mineral pigmentsand fillers, and other inert powders may be used for this purpose.Coloring agents are particularly desirable, in improving the appearanceof the final product. Resinous grit such as is here used for theanti-skid layer, but reduced to a much finer particle size, may be addedas filler.

With regard to the resinous grit material itself, all things considered,the sized particles obtained on crushing relatively massive thermallycured phenol-aldheyde mouldings containing a high percentage of inertfiller and having a Moh hardness value of about 3 are generally to bepreferred. Particles of the approximate size identified in the examplehave been most useful, but a considerable range of particle size, forexample from 24 mesh to 150 mesh, is permissible. As hereinbefore noted,a preferred phenolic raw material is available as a waste product fromthe plastics industry. For special purposes, and where the added expenseis of no particular consequence, phenolic mouldings containing a muchlower proportion of inert filler, or mouldings containing special typesof filler, such as specific colored pigments or fibrous material, oreven unfilled moulded phenolic resin products, may replace the mouldedradio cabinets, telephone hand sets and the like specifically mentionedherein as source material for my resinous particles. Many examples ofsuch compositions have been found to possess toughness, resiliency,impact resistance, etc. to a desirable degree, particularly as evidencedby their ability to be reduced to desired grit size without excessiveformation of fines.

Resins or equivalent materials other than phenolic resins, and havingthe desired hardness value and crushability factors, may be used in manyinstances, but are found to be in general less desirable. Thus,aminoaldehyde resin masses having a Mob scale hardness value of about 3have been reduced to the proper particle size and bonded, by means ofphenolic resin binding and sizing compositions, to impregnated fabric,as in the above example. The resulting product was effective as ananti-skid surfacing under dry conditions, but the grit broke up and lostits effectiveness under use conditions involving the continued presenceof Water. Furthermore, the sheet material curled when dampened prior toapplication, and was then difficult to apply smoothly to flat surfaces.

The relative weights, or more significantly the relative volumes, ofbinding and sizing composition and of resinous grit material may bevaried widely in making my improved type of surfacing. Minimum. amounts,both of binder and of surface size, which are required to provideeffective anchoring of a desired quantity of resinous particles of anyspecific diameter or particle size may readily be determined. Theproduct is somewhat more flexible than more heavily bonded sheets, andis also somewhat less costly to produce. increasing the amount of binderincreases the number of particles which may be retained per unit area,and also increases the life of the sheet in use. The amount of surfacesizing is ordinarily controlled so as to provide complete covering andeffective anchoring of each particle without completely filling thevalleys between particles. However, where a particularly long-wearingsurface is de sired at the expense of a somewhat reduced effectivenessas an anti-skid material, the amount of sizing coat may be increased soas to form a continuous smooth outer surface. Such a product has meritas a long-wearing and fire-resistant floor covering, and has beensuggested as a replacement for linoleum. in this type of product, theaddition of finely divided resinous filler to the resinous binder andsurface size, as hereinbefore mentioned, is particularly appropriate.

My flexible resinous anti-skid surfacing sheet i lay be affixed toflight decks or other surfaces in a number of ways, but I prefer at thepresent time to employ solventtype adhesive cements for this purpose.One such cement, which has given excellent results for the specificpurpose here emphasized, consists of a solution in a volatile organicsolvent of a blend of pigmented polymerized chloroprene and acompatible, oilsoluble, heatadvancing phenol-aldehyde resin. T he liquidadhesive cement is ordinarily applied to both surfaces, e. the decksurface and the back of the anti-skid sheet, and is allowed to dry; oneor both of these coatings is then re activated, either by heating or bythe application of a thin surface coating of dilute adhesive cement orof solvent, and the strip is pressed in place and held until the bond iscompleted. The surfacing sheet may be furnished to the user as apro-coated sheet, requiring only activa tion of the adhesive coating byheat or solvent.

The sheet material may also be adherently attached to various surfacesby means of normally tacky and pressuresensitive adhesives. Thus, onetype of my anti-skid sheet material is first lightly coated or primed onthe back surface with a dilute solution of the polychloroprene-phenolicresin adhesive cement, and is subsequently coated with a heavier layerof a high-strength normally tacky and pressure-sensitive adhesive, whichis then protected with a temporary liner such as Holland cloth.

By means of the invention described hereinabove, I provide a new productof widespread utility, and having particular advantages as a componentof anti-si id deck surfaces on aircraft carriers. One embodiment of myinvention is in the form of a flexible pro-formed sheet ma terialsuitable for adhesively bonding to deck surfaces or the like, and havingan anti-skid surface layer comprising firmly bonded sized particles ofwater-resistant thermally cured phenolic resin mouldings. he anti-skidsurface thus produced is substantially equivalent in anti-skid properties to similar surfaces made with mineral abrasive grit particles,yet has no abrasive action on steel cables. Surprisingly, in spite ofthe vastly lower hardness or abrasive factor, the new all-resin productis also superior in wear-resistance to the mineral-granule type.

I claim:

1. Flexible unitary sheet material having a rough antiskid surface layerof improved wear-resistance and which is non-abrasive and non-sparkingtoward steel, said sheet material comprising, in order, a flexiblewater-resistant fibrous supporting base, a water-resistantnon-thermoplastic grit bond, and a layer of firmly bonded, tough andresilient angular resinous grit particles having a Moh scale hardnessvalue of about 3 and a particle size in the range of about 24-150 mesh.

2. Sheet material according to claim 1 and having, on the surfaceopposite the anti-skid surface, a firmly'bonded non-tacky coating of asolvent-activatible Water-resistant adhesive cement.

3. Sheet material according to claim 1 and having, on the surfaceopposite the anti-skid surface, a firmly bonded coating of a normallytacky and pressure-sensitive adhesive.

4. A structure comprising a walkway having a surface and, adhesivelybonded thereto to form an anti-skid surface covering, sheet materialaccording to claim 3.

5. Flexible unitary sheet material having a rough antiskid surface layerof improved wear-resistance and which is non-abrasive and non-sparkingtoward steel, said sheet material comprising, in order, a flexible,water-resistant, impregnated fibrous supporting base, a water-resistantresinous grit bond, and a layer of firmly bonded, tough and resilientangular grit particles of Water-resistant, thermally cured phenolicresin having a Moh scale hardness value of about 3 and a particle sizein the range of about 24-150 mesh.

6. Flexible sheet material having a rough anti-skid surface layer ofimproved wear-resistance and which is non-sparking and non-abrasivetoward steel, said sheet material comprising, firmly bonded together inthe order indicated, a flexible, water-resistant, impregnated fibroussupporting base, a water-resistant phenolic resin grit bond, and a layerof firmly bonded, tough and resilient angular resinous grit particleshaving a Moh scale hardness value of about 3 and a particle size in therange of about 24-150 mesh.

7. Flexible unitary sheet material having a rough antiskid surface layerof improved wear-resistance and which is non-sparking and non-abrasivetoward steel, said sheet material comprising, in order, a flexible,water-resistant, impregnated fabric supporting base, a water-resistantphenolic resin grit bond, and a layer of firmly bonded, tough andresilient angular resinous grit particles having a Moh scale hardnessvalue of about 3 and a particle size in the range of about 50-80 mesh.

8. Flexible unitary sheet material having a rough antiskid surface layerof improved wear-resistance and which is non-sparking and non-abrasivetoward steel, said sheet material comprising, in order, a flexible,water-resistant, impregnated fabric supporting base, a water-resistantphenolic resin grit bond, and a layer of firmly bonded, tough andresilient angular grit particles of water-resistant, thermally curedphenolic resin containing about 50-80% of inert filler and having a Mohscale hardness value of about 3 and a particle size in the range ofabout 50-80 mesh.

9. Sheet material according to claim 8 and having, on the surfaceopposite the anti-skid surface, a firmly bonded coating of a normallytacky and pressure-sensitive adhesive.

10. Flexible sheet material having a rough anti-skid surface layer ofimproved wear-resistance and which is non-sparking and non-abrasivetoward steel, said sheet material comprising, firmly bonded together inthe order indicated, a flexible, water-resistant,thermoplastic-resinimpregnated fabric supporting base, a water-resistantphenolic resin grit bond, a layer of firmly bonded, tough and resilientfully cured phenolic resin angular grit particles having a Moh scalehardness value of about 3 and a particle size in the range of about24-150 mesh, and a surface sizing layer of phenolic resin.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Ellis, The Chemistry of Synthetic Resins, Reinhold Publ.Corp., New York, vol. 1, 1935, pages 455, 462, 463.

1. FLEXIBLE UNITARY SHEET MATERIAL HAVING A ROUGH ANTISKID SURFACE LAYEROF IMPROVED WEAR-RESISTANCE AND WHICH IS NON-ABRASIVE AND NON-SPARKINGTOWARD STEEL, SAID SHEET MATERIAL COMPRISING, IN ORDER, A FLEXIBLEWATER-RESISTANT FIBROUS SUPPORTING BASE, A WATER-RESISTANTNON-THERMOPLASTIC GRIT BOND, AND A LAYER OF RIRMLY BONDED, TOUGH ANDRESILENT ANGULAR RESINOUS GRIT PARTICLES HAVING A MOH SCALE HARDNESSVALUE OF ABOUT 3 TO A PARTICLE SIZE IN THE RANGE OF ABOUT 24-150 MESH.